Internal combustion engine in which the fuel is preheated



Jan. 21, 1936. o. SIMMEN 2,028,527

INTERNAL COMBUSTION ENGINE IN WHICH THE FUEL IS PREHEATED Filed Nov. 23, 1954 5'2; 75 25 iii Patented Jan. 21, 1936 UNITED STATES INTERNAL COMBUSTION ENGINE IN WHICH THE FUEL IS PREHEATED Oscar Simmen, Winterthur, Switzerland, assignor to Sulzer Frres, Socit Anonyme, Winterthur,

Switzerland Application November 23, 1934, Serial No. 754,402 In Switzerland December 4, 1933 Claims. (Cl. 123-427) The invention relates to an internal combustion engine in which the fuel is preheated. 'As is well known in internal combustion engines the combustion of heavy oils, i. e. fuel containing asphalt, is accompanied with great difliculties, specially when the fuel is injected without air. In an internal combustion engine according to the present invention these difficulties are overcome by heating the fuel, before it is led to the fuel pump, under a pressure generated by means of a delivery device or a pressure medium, thus avoiding any evaporating of the fuel. Preferably the pressure is adjustable and higher than the evaporating pressure of the water contained in the fuel, corresponding to the preheating temperature. Also the preheating temperature chosen may be such that the preheated fuel has a viscosity at the maximum of 8 Engler. Further the fuel pump may be provided with a heating jacket through which the surplus of preheated fuel is passed.

Two examples of construction according to the invention are shown diagrammatically in the accompanying drawing.

Fig. 1 shows an internal combustion engine with a device for preheating the fuel and putting it under pressure before it is admitted into the fuel pump.

Fig. 2 is a variant of Fig. 1. i

The internal combustion engine I in Fig. 1 has a fuel pump 2, the drive of which is for simplicitys sake not further illustrated. The fuel pump 2 delivers the fuel through the pipe 4 to the injection valve 5 in the cylinder covers 1. From the tank 8 fuel is drawn in through the suction pipe 9 by the pump I 0 and delivered through the delivery pipe ll into the delivery tank l2. From the delivery tank [2 the pipe l3 leads to the stop valve M, to which the suction pipe I 6 of the fuel pump 2 is connected. The pipe I! is surrounded by a heating jacket IT, to which the heated cooling water flows from the cylinder cover I through the pipe l8; through the pipe I9 it is led away. Within the widening of the exhaust gas pipe 2|, the pipe I3 is divided and the two pipes 22 are provided with ribs in order to ensure good heat transmission. From the pipe l3 the pipe 23 with the regulating valve 24 branches off to the tank 8. By means of the pipe 26, which can be shut off by means of the valve 25, compressed air, which may be taken for example from the starting-air bottles, can be introduced into the tank l2.

The method of operation is the following. The fuel in tank 8 is heavy oil, and a lighteroil is injected for starting the internal combustion engine I. Therefore the flow of heavy oil tothe fuel pump 2 is first of all shut off by means of the fuel valve l4, and the valve 21 is opened, thus allowing light oil to be led from the tank 28 to the pipe 30 to the fuel pump 2. Meanwhile the heavy oil is put under pressure by means of the pump l0, before it is introduced into the fuel pump 2, and is preheated by the hot cooling water in the heating jacket I! and also by exhaust gases in the parts 22 of the pipe [3 provided with ribs. The heating of the fuel in pipe H can be regulated by adjusting the quantity of cooling water by means of the stop cock 3|. When the heavy oil has been sufiiciently heated, the valve 2'! is closed and the valve l4 opened so that the fuel pump 2 from that moment delivers heavy oil.

In order to regulate the temperature of the heavy oil in still another manner, the quantity of fuel delivered by the pump I0 is regulated before the fuel pump 2 by means of the regulating valve 24, the surplus of fuel flowing back through pipe 23 into the tank 8. The pressure of the fuel before the fuel pump 2 can be regulated not only by means of the pump in, for example by altering its speed and the quantity flowing through the overflow valve 24, but also by opening the valve and the compressed air pipe 26 on the tank I2. This causes a constant pressure to be exerted-on the fuel in the tank l2 independently of the fuel consumption. This additional pressure from the compressed air piping of the internal combustion engine is not required in all cases. The drive of the fuel pump 2 in Fig. 1 is shown in Fig. 2.

In Fig. 2 the tank 33 itself is surrounded with a jacket 34, whereby the warmed cooling water coming from the cylinder cover through the pipe 18. which is provided with the regulating valve 3i, enters into the jacket 34 and flows away through the pipe 35. The fuel is withdrawn from the tank 33 by the pump 3'! and arrives at the suction valve 44 of the fuel pump 2 through the pipe 38 with the piece 39 provided with ribs in the widening 4|] of the exhaust pipe 2! through the valve 4|, the pipe 42 and the suction pipe 43. Branches 46, 41 are provided before and after the valve 4i and are fitted with closing members 48, 49 and furnished with ribs within the widening of the exhaust pipe. The two branches 46, 41 pass over to the bypass pipe 5| which is shut off from the pipe 42 by means of the valve 52.

The pipe 42 is separated from the suction pipe 43 by the three-way cook 53. As a third pipe, the

suction pipe 43 from the pipe 42 by means of the three-way cook 53 and leading light oil from the tank 28 to the fuel pump 2, whilstthe pump-31 circulates the fuel over the heating elements 39, 46, and 41 in order to bring it to the required preheated temperature. When puttingall the ribbed pipes 39, 46, and 41 into operation, the valves 4| and 52 are closed and the valves 48 and 49 opened, so that the fuel arrives first'of-all in the ribbed pipe 39, and then in theribbed pipe 46 and finally in the ribbed pipe 41 and from there through the valve 49 to the pipe 42, after which it returnsithrough the three-Way cook 53 and 51; which; are then-in position II, through thepipes 59, back again to the fuel tank 33.

If ,however, the heated heavy oil isto flow back throughthfi. jacket of the fuelpump 2, the threeeway-cockfilis brought into the position I, so. that-the lheated fuel flows throughv the jacket fiflgtoe pipe, .59;

Foriregulatingthe heat taken from the exhaust gases, the ribbed pipes 41 and 46 can be putout ofroperation, whereby, if two ribbed pipes are putjnto-bperation, the fuel fiows through the ribbedypipe.39 with the valve 48 open and through the ribbed-:pipe 46 ;with the valve 4| closed, arriving; at; pipe 42; through the bypass 5!, with valve52open, andvalve 49 closed. If only one ribbed pipe is-put out of operation the valves 48, 49, and 52 remain closed and the valve-4i open.

The-ribbed-pipes 46, 41 are emptied when out ofioperation, in order to-prevent evaporating-or cokingof the fuel'remainingin them. For this purpose. the cocks-65, 66-and6'1are-used. When puttingithe. ribbed tube 41:0ut of operation, the three-way cock 6:1. is turned from position III into position IV'; so that the ribbed pipe 41 is shut off from the pipe 5| but connected with the pipe. 69 which leads to the fuel tank 8. After that, the .cock.-;-is turned from position VI to position VII; iniorderthat the-connection 10 on the compressed-air pipe is connected with the ribbed :tube 4fl'and compressed air can empty the pipe flz;- If the pipe 46 isput outof; operation in addition to the pipe 41, the three-way cocke51-isturned into positionV with cocks 52, 49, and 4,8;closed, and then the cock 46-is also turned from position V-I into position VII. If a ribbed pipe-which has-been; emptied-is again put into circuit, it is first'of all filled with fuel by bringing the cock 65' or the cocks 65 and 66 into position-VIII so that the ribbed pipes are given directly a'free outlet for the air-with the .valves 49 and 48'stillclosed. The cocks 65, 66 are brought back into'position VI as soon as the fuel issues from the open overflows 1|.

As-soon asthe fuel is sufficientlywarm, cook 21 isclosed and the three-way cook 53 is brought backinto position I, so that the heavy oil; which hasbeen put under pressure by means of the pump it! and preheated in tank 33 and inexhaust pipe 2 l is now led to the fuel-pump 2, and therebydelivered into the injectionvaive 5. Thisvalve works automatically in a manner known initself, in that theinozzle is closed by means of a needle loaded with a spring. During. inj-ection the needle :is raised under the influenge ;of; the -fuel pressure. Illustration of this is omitted for the sake of simplicity. The needle could also be controlled automatically from the shaft of the cam 63. By turning the three-way cook 51 into position I, the fuel pump 2 is preheated also when injecting heavy oil, and the quantity of oil circulated can be regulated by means of the valve 54.

It may easily happen that some water is contained in the fuel. Consequently, in known devices for-injecting fuel, the water vapour and the gas bubbles are led away from the heated fuel, since preheating with the known devices occurs only under natural pressure, i. e. exclusively under the-influenceof gravity. The evaporating pressure of the water contained in the fuel corresponding' to the preheating temperature, is already so high in the case of preheating temperatures of 70 C. and more, that when in order to avoid steam bubbles in the fuel, which adversely influences the delivery of the injection of the fuel, a pressure higher tharrthis evaporating; pressure is adopted, this-pressure can no longer be a natural pressure but must be caused-artificially by-rneans of a delivery device or a pressure medium. The preheating temperature of the fuel is als dependenton the viscous properties of the fuel. The preheating temperature for heavy oil should be at least sohigh that the preheated fuel has a viscosity of at the most 8 Engler in order toobtain 'injectiomwhich is at least fairly good.

The advantage of-circulating the fuel consists in-that the preheating temperature can be more exactly-regulated, and this regulation is in certainrespects-independent of the exhaust gas temperature,

When regulating the artificial pressure on the fuel before thefuel pump by means of the introdugtion Off compressed air to tank I2 or 33, the preheating-temperature can be regulated either by setting the closing member 24 'or- 54 by hand, or maintained atv a; constant value by means of thermostats; This necessitates a double. regulation of the pressure and of thetemperature.

Itjs also; possible, however, to fit a regulating valye 12 in-the pipe 9, as shown in Fig. 1, whereby the gear wheel pump;l0 delivers a constant quantity of fuel. The pressure in the whole system is kept constant in thatthe regulating valve 24 is at the sarne time-designed as an automatic pressure regulating'valve which opens further in consequence of-the rise in pressure and leads back through pipe 23 to-tank 8 as much fuel as is necessary-to lower the pressure to the predetermined value, In this case-the valve 25 is closed. Finally,

the,-artificial pressure of the fuel can also be kept constant and the preheating temperature altered in accordance with the load, in that the system is setto. givea sufiicient preheating of the fuel at the lowest-load and the artificial pressure is so high that evaporation of the fuel at the maximum loadis prevented. In this case the regulating valve 24 is open only for an initial circulation of the. fuel, butis closed in service, as is also the valve.,25.

In certain cases the connection 26 of the tank l2 to the compressed air system of the internal combustion engine I may be entirely omitted and the constant artificial pressure of the fuel is maintained through the bypass pipes 13 with the pressure regulating-valve 14, in that the regulating valve, 14 is set to a predetermined pressure and leads any surplus back to the tank 8. The regulating valves may be adjustable, for example in dependencev on the. kind of fuel.

Further, circulating the fuel by means of a pump 31, whereby the fuel flows back into the pressure tank, gives the advantage that losses of heat and pressure in the fuel are avoided in comparison with the method of leading the fuel into a storage tank which is not under pressure. The adoption of an automatic or controlled injection valve has the advantage that the height of the preheating temperature is not limited by the conditions existing between fuel pump and working cylinder, in that in long pipes the formation of steam or gas bubbles between the two, and consequently a rather inaccurate injection, is avoided.

I claim:

1. In an internal combustion engine the combination of a pump for injecting liquid fuel into the engine cylinders, means for preheating the fuel prior to its delivery to said pump to a temperature at which vaporization of the more volatile constituents of the fuel would take place at atmospheric pressure, means for maintaining said fuel during preheating and its subsequent delivery to the fuel pump under a pressure suflicient to prevent vaporization of the more volatile constituents contained in said fuel.

2. In an internal combustion engine, the combination of a liquid fuel supply, a pump for injecting fuel into the engine cylinders, conduits for conducting fuel from said fuel supply to said in jection pump, a pump for forcing fuel from said fuel supply to said injection pump, and means for preheating the fuel between said pumps to a temperature at which vaporization of the more volatile constituents of the fuel would take place at atmospheric pressure, the pump for forcing the fuel from the fuel supply to the injection pump exerting a force on the fuel sufficient to prevent vaporization of the more volatile constituents contained in the fuel.

3. A combination as set forth in claim 1 in which means are provided for varying the pressure on the fuel during preheating and delivery to the fuel pump.

4. A combination as set forth in claim 1 in which the pressure on the fuel during preheating and delivery to the fuel pump is greater than the evaporating pressure of water contained in the fuel.

5. A combination as set forth in claim 1 in which the fuel is preheated so that it has a viscosity at the maximum of 8 Engler.

6. A combination as set forth in claim 1 in which a circulatory system is provided for the preheated fuel.

'7. A combination as set forth in claim 1 in which valve-controlled conduits are provided for bypassing fuel from the engine cylinders when desired.

8. A combination as set forth in claim 1 in 7 as the means for preheating the fuel.

11. A combination as set forth in claim 1 in which the exhaust gases passing through the exhaust conduit are utilized as a source of heat for preheating the fuel and in which a plurality of passages for fuel are provided in said exhaust conduit and in which means are provided for bypassing at least one of the passages for the fuel located in said exhaust conduit.

12.. A combination as set forth in claim 1 in which the exhaust gases passing through the exhaust conduit are utilized as a source of heat for preheating the fuel and in which a plurality of passages for fuel are provided in said exhaust conduit and in which means are provided for bypassing at least one of the passages for the fuel located in said exhaust conduit, and in which means are provided for draining fuel from the fuel passages in the exhaust conduit which have been bypassed.

13. A combination as set forth in claim 2 in which a conduit is provided for bypassing fuel from the outlet side of the pump for forcing fuel from the fuel supply to the injection pump, and in which said bypassed conduit is provided with pressure-regulating means which maintains the fuel being forced from the fuel supply to the fuel injection pump under a predetermined pressure.

14. A combination as set forth in claim 1, in which the internal combustion engine is provided with a water-cooling jacket and in which cooling water from said jacket is utilized as the preheating means for the fuel.

15. A combination as set forth in claim 1 in which compressed air is utilized at least in part for maintaining fuel under pressure during preheating.

OSCAR SIMMEN. 

